Storm Forecast
Valid: Sun 13 Jan 2019 06:00 to Mon 14 Jan 2019 06:00 UTC
Issued: Sat 12 Jan 2019 21:09
Forecaster: TUSCHY

A level 1 was issued across most of Germany and Benelux mainly for severe wind gusts. A low-end tornado risk exists.

A level 1 was issued across W-Syria mainly for excessive rain and an isolated tornado risk.

SYNOPSIS

The blocking pattern persists with a deep/warm anticyclone over the far E Atlantic and numerous digging troughs to its east, which affect most of N/CNTRL and E-Europe. Overall advective regime of rather dry and cold air suppresses thunderstorms over most parts of Europe. Temporal intrusions of more humid air from the Atlantic and some offshore areas however could see adequate CAPE for a few thunderstorms.

DISCUSSION

... E-Mediterranean ...

An eastward moving upper wave affects this area and causes overlapping low-tropospheric moisture with somewhat steeper mid-level lapse rates. Arising low to moderate SBCAPE, weak CIN and deep forcing result in scattered onshore moving thunderstorms with heavy rain and graupel the main hazard. A tornado/waterspout risk exists

- along the coast of W-Syria, where LL shear increases and
- over offshore areas over the E Mediterranean with enough LLCAPE for an augmented waterspout risk

Combined rainfall and tornado risk resulted in an upgrade to a level 1 for parts of the coastal areas.

... Parts of Germany and Benelux ...

A cold front passage is anticipated beyond noon over most of Germany/Benelux within the left exit region of a 50 m/s mid-level speed max. Cross sections however reveal an ill-defined looking low-tropospheric front with a weak/smooth wind shift signature and limited forcing. Therefore confidence in an organized convective line is low despite some CAMs indicating at least short/broken line segments. The weak thermal gradient also causes LL directional shear to remain modest next to the front, although slight cell track deviation from the mean wind could boost LL shear/helicity substantially given the strong environmental speed shear (in a low LCL environment). Hence an isolated tornado risk can't be discounted although the main hazard will be numerous severe wind gusts with 25 m/s 850 hPa background flow.
We kept this level 1 surrounded by a low prob. lightning area, as forecast profiles show only very slim CAPE in the graupel region. Due to the missing LL forcing the level 1 had to be expanded over a vast area to account for the wind gust risk with any short-lived electrified convection, probably scattered over a broad area.

... W-Norway ...

Potential onshore moving (numerous) nocturnal polar low(s) could result in enhanced probabilities for isolated thundersnow with near blizzard conditions over a confined area. Numerical models still have a bad handling on that feature/those featurs, so we stick with the broad low prob. lightning area due to very cold mid-levels and improved LL moisture input from the Barents Sea.